ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 161

• Manufacturer Part Number: ATmega88PA Automotive
• Manufacturer: Atmel Corporation

20.4.4
20.5
20.5.1
7701E–AVR–02/11
Register Description
Programming Time for Flash when Using SPM
SPMCSR – Store Program Memory Control and Status Register
Flash corru ptio n ca n e asily b e avoided by fo llowing at lea st one the se d esig n
recommendations:
1. Keep the Atmel
2. Keep the AVR core in power-down sleep mode during periods of low VCC. This will
The calibrated RC Oscillator is used to time Flash accesses.
gramming time for Flash accesses from the CPU.
Table 20-1.
Note:
The Store Program Memory Control and Status Register contains the control bits needed to
control Program memory operations.
• Bits 7..5 – Res: Reserved Bits
These bits are reserved bits in the ATtiny24/44/84 and always read as zero.
• Bit 4 – CTPB: Clear Temporary Page Buffer
If the CTPB bit is written while filling the temporary page buffer, the temporary page buffer will
be cleared and the data will be lost.
• Bit 3 – RFLB: Read Fuse and Lock Bits
An LPM instruction within three cycles after RFLB and SPMEN are set in SPMCSR will read
either the lock bits or the fuse bits (depending on Z0 in the Z-pointer) in the destination regis-
ter. See
• Bit 2 – PGWRT: Page Write
If this bit is written to one at the same time as SPMEN, the next SPM instruction within four
clock cycles executes Page Write, with the data stored in the temporary buffer. The page
address is taken from the high part of the Z-pointer.
Bit
0x37 (0x57)
Read/Write
Initial Value
Flash write (Page Erase, Page Write,
and write Lock bits by SPM)
voltage. This can be done by enabling the internal Brown-out Detector (BOD) if the
operating voltage matches the detection level. If not, an external low V
tion circuit can be used. If a reset occurs while a write operation is in progress, the
write operation will be completed provided the power supply voltage is sufficient.
prevent the CPU from attempting to decode and execute instructions, effectively pro-
tecting SPMCSR and, thus, the flash from unintentional writes.
1. The min and max programming times are per individual operation.
“EEPROM Write Prevents Writing to SPMCSR” on page 160
SPM Programming Time
Symbol
R
7
0
–
®
AVR
®
R
6
0
–
Atmel ATtiny24/44/84 [Preliminary]
RESET active (low) during periods of insufficient power supply
R
5
–
0
(1)
Min Programming Time
CTPB
R/W
4
0
3.7 ms
RFLB
R/W
3
0
PGWRT
Table 20-1
R/W
2
0
Max Programming Time
PGERS
for details.
R/W
1
0
shows the typical pro-
CC
reset protec-
4.5 ms
SPMEN
R/W
0
0
SPMCSR
161